A packet of cigarettes normally comprises an inner package defined by a group of cigarettes wrapped in a sheet of wrapping material; and an outer package enclosing the inner package, and which may be defined by a sheet of wrapping material folded into a cup shape about the inner package (soft packet of cigarettes), or by a rigid, hinged-lid box formed by folding a rigid blank about the inner package (rigid packet of cigarettes).
In a conventional packet of cigarettes, the group of cigarettes is wrapped internally in a rectangular sheet of foil inner wrapping material with no glue, and is packed externally in a rectangular sheet of outer packing material which is stabilized using glue.
Tobacco is highly sensitive to environment. That is, in contact with the atmosphere, its organic characteristics tend to vary alongside variations in humidity (by losing or absorbing too much moisture) or due to evaporation of the volatile substances with which the tobacco is impregnated (especially in the case of aromatic cigarettes treated with spices). To preserve the tobacco, packets of cigarettes are therefore cellophane-wrapped, i.e. wrapped in a heat-sealed overwrapping of airtight plastic material. This, however, may not always be sufficient to fully preserve the tobacco in the packet, especially if the packet is consumed some time after manufacture. Moreover, when the packet is unsealed, the overwrapping is removed, thus exposing the tobacco to the atmosphere, and, if the cigarettes are not consumed soon after the packet is unsealed, the organic characteristics of the remaining cigarettes may deteriorate.
In an attempt to eliminate this drawback, U.S. Pat. No. 4,300,676A1 proposes a rigid packet of cigarettes, in which the inner package is airtight, and comprises a sheet of airtight, heat-seal wrapping material having a cigarette extraction opening.
It has been observed that folding the sheet of inner wrapping material about the group of cigarettes may damage the ends of the cigarettes, thus resulting in localized deformation (of both the filter ends and the plain ends where the tobacco is exposed), and/or tobacco spill (i.e. tobacco fallout, obviously only from the plain ends where the tobacco is exposed). This applies in particular to the corner cigarettes in the group, though damage is also evident in all the outermost cigarettes, i.e. located along the fold lines of the sheet of inner wrapping material. Folding a sheet of airtight inner wrapping material is especially damaging to the cigarettes, on account of airtight sheets being thicker (and therefore stiffer) than conventional sheets of foil inner wrapping material. In the packet of cigarettes described in U.S. Pat. No. 4,300,676A1, the sheet of airtight inner wrapping material is preferably folded into a U at the filters of the cigarettes, so that the filters are located at the extraction opening, as in practically all currently marketed packets of cigarettes. When folding the sheet of airtight wrapping material into a U, however, the filters of the cigarettes are subjected to severe mechanical stress. It is important to bear in mind that the filters are visible when the packet is opened, so any deformed filters are particularly negative by giving the impression the cigarettes are flawed. Moreover, the above wrapping method fails to provide for forming square edges at the filters, on account of the stiffness of the sheet of inner wrapping material deforming the filters and so resulting in the formation of rounded edges. The fact that the inner package is rounded as opposed to square is particularly undesirable, by resulting in an overall look of the visible portion of the inner package that is not very popular with consumers, who tend to opt for inner packages with decidedly sharp edges.